1. Field of the Invention
The present invention relates to a system and method for detecting and signalling the drowsiness of an automotive driver in which the driver's drowsy driving behavior is recognized on the basis of the number of steering adjustments within a predetermined interval of time, and the number of steering reversals within the predetermined interval of time.
2. Description of the Prior Art
Japanese Utility Model Registration Publication No. 57-57126 discloses a system for determining the driver drowsiness wherein the system determines that the vehicle driver is steering drowsily depending on the number of steering pulses, each steering pulse being produced whenever the steering wheel is rotated through a predetermined angle, within a predetermined period of time. The disclosure of the above-described publication is incorporated by reference.
However, the system disclosed in the above-described publication has the problem of occasionally recognizing drowsiness erroneously. For example, when the vehicle is travelling along an unpaved road, there will tend to be more frequent steering adjustments than when the vehicle is travelling along an paved road due to the necessity for the driver to correct the direction of the vehicle a number of times according to the holes and bumps in the unpaved road surface. In addition, the driver may purposefully turn the steering wheel back and forth rapidly in an attempt to remain alert. In these cases, the system might make an erroneous determination of the driver's drowsiness. For this reason, detection accuracy cannot be ensured only on the basis of the number of steering pulses.